Gamma:
This is a mathematical function used to describe the relationship between input and output levels, and measures the level of compression or expansion of dark or light shades in an image.

GDI (Graphic Display Interface):
An easily manipulated on-screen interface permitting direct click-on interaction with program commands. It is a library of video display and printer functions for 2D graphics.

Gouraud shading (smooth shading):
A method of shading polygons, where each color is initially calculated at each of the vertices in a polygon. The polygon's surface is then shaded to give a smooth transition between colors at each vertex, consequently smoothing the appearance of adjacent polygons. The replacement of texture with shading for 3D objects that are too far away to be perceptible saves processing time.

Graphics:
The representation of all non-text that appears on-screen.

Graphics accelerator:
A board which provides the PC with a separate processor on which to offload graphics oriented tasks, and thus freeing up valuable CPU time. This obviously improves graphics-intensive software performance.